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Entry 5 senses · 2 variants Webster, 1913

Spiral

/spīr'-əl/ · Spi·ral · IPA /ˈspaɪɹəl/
01 a. Winding or circling round a center or pole and gradually receding from it; as, the spiral curve of a watch spring.
  1. 1.
    Winding or circling round a center or pole and gradually receding from it; as, the spiral curve of a watch spring.
  2. 2.
    Winding round a cylinder or imaginary axis, and at the same time rising or advancing forward; winding like the thread of a screw; helical.
  3. 3.
    Of or pertaining to a spiral; like a spiral.(Geom.)
Phrases & compounds
Spiral gear — a gear resembling in general a spur gear, but having its teeth cut at an angle with its axis, or so that they form small portions of screws or spirals.
Spiral gearing — a kind of gearing sometimes used in light machinery, in which spiral gears, instead of bevel gears, are used to transmit motion between shafts that are not parallel.
Spiral operculum — an operculum whih has spiral lines of growth.
Spiral shell — any shell in which the whorls form a spiral or helix.
Spiral spring — See the Note under Spring, n., 4.
02 n. A plane curve, not reentrant, described by a point, called the generatrix, moving along a straight line according to a mathematical law, wh…
  1. 1.
    A plane curve, not reentrant, described by a point, called the generatrix, moving along a straight line according to a mathematical law, while the line is revolving about a fixed point called the pole. Cf. Helix.(Geom.) See: Helix
  2. 2.
    Anything which has a spiral form, as a spiral shell.
Phrases & compounds
Equiangular spiral — a plane curve which cuts all its generatrices at the same angle. Same as Logarithmic spiral, under Logarithmic.
Spiral of Archimedes — a spiral the law of which is that the generatrix moves uniformly along the revolving line, which also moves uniformly.